WO2010107017A1

WO2010107017A1 - Optical signal level adjustment system, apparatus which analyzes information and generates control signal for system of same, and method of analyzing information and generating control signal

Info

Publication number: WO2010107017A1
Application number: PCT/JP2010/054410
Authority: WO
Inventors: 井上　貴則
Original assignee: 日本電気株式会社
Priority date: 2009-03-19
Filing date: 2010-03-16
Publication date: 2010-09-23
Also published as: EP2410677B1; US20110311216A1; EP3553972A1; EP2410677A4; JP2010226167A; EP3553972B1; EP2410677A1; JP5240673B2; CN102342043A; US8798473B2

Abstract

An optical signal level adjustment system able to prevent transmission characteristics from deteriorating due to the nonlinear effects in the transmission path caused by increases in channel power when a cable disconnection failure occurs. The method for this system is provided with: a step of finding the location at which optical signal disconnection has occurred, based on the detection of optical signal disconnection in units of wavelength blocks by a signal disconnection detection unit included in each terminal station apparatus, finding a combination of a wavelength block and terminal station apparatus requiring adjustment of transmission dummy light corresponding to said location, and finding a dummy light adjustment amount; and a step of transmitting, to the terminal station apparatus requiring adjustment of the transmission dummy light, a control signal for adjusting the strength of the dummy light in the wavelength block exactly by the dummy light adjustment amount.

Description

Optical signal level adjustment system, information analysis / control signal generation apparatus and information analysis / control signal generation method in this system

The present invention relates to an optical signal level adjustment system, an information analysis / control signal generation apparatus and an information analysis / control signal generation method in the system, and in particular, an optical signal that can be applied to an optical submarine cable system or a land optical communication system. The present invention relates to a level adjustment system, an information analysis / control signal generation apparatus and an information analysis / control signal generation method in the system.

Normally, in order to perform channel power management when a cable is disconnected, the output of an optical repeater is adjusted or a switch circuit is mounted in a BU (Branching Unit). However, the circuit is complicated and expensive.
In Patent Document 1, dummy light (ASE light) is arranged in a wavelength channel non-mounted band, and the power is controlled at the time of expansion, so that the optical power of the entire band can be kept constant regardless of the number of multiplexed wavelengths. It is disclosed. Japanese Patent Application Laid-Open No. H10-228561 discloses the optical power of add light to be inserted. Further, Patent Document 2 describes a configuration in which dummy light output adjustment is performed by analyzing a signal level measured by an optical spectrum analyzer installed in a receiving terminal station as a third embodiment.

JP 2005-051598 A JP-A-10-150433

However, measures against optical power fluctuations caused by the occurrence of a failure are not disclosed in any patent document.
Further, Patent Document 1 does not include an optical add / drop device in the configuration, and does not describe a method for compensating for the difference between the signal level on the trunk side and the signal level on the branch side.

When a cable disconnection failure occurs in a submarine cable system that employs an optical add / drop device (hereinafter referred to as OADM-BU (Optical Add-Drop Multiplexing-Branching Unit)), the signal that should be inserted is not multiplexed. The number of channels is reduced. Since the repeater output in the submarine cable system is almost constant, reducing the number of main signal channels leads to an increase in channel power. As channel power increases, transmission characteristics degrade due to nonlinear effects in the transmission path. For this reason, management of the main signal channel power at the time of cable disconnection failure is very important.

Therefore, the present invention provides an optical signal level adjustment system and an optical signal level that can prevent deterioration in transmission characteristics due to nonlinear effects of a transmission path due to an increase in channel power when a cable disconnection failure occurs. The purpose is to provide an adjustment method.

According to the present invention, based on the optical signal interruption in units of wavelength blocks detected by the signal interruption detection unit included in each terminal device at each location, the location where the optical signal failure occurred and the transmission dummy light corresponding to that location A step of obtaining a set of a terminal station device and a wavelength block to be adjusted and a dummy light adjustment amount; and an intensity of the dummy light in the wavelength block by the dummy light adjustment amount to the terminal device to adjust the transmission dummy light. And a step of transmitting a control signal for adjusting. An optical signal level adjusting method is provided.

Further, according to the present invention, an optical signal interruption is detected on the basis of a signal interruption detector that detects an optical interruption signal in units of wavelength blocks and an optical signal interruption detected by a signal interruption detector included in each terminal device. A portion where the transmission dummy light according to the location is adjusted, a portion for obtaining a set of wavelength blocks and a dummy light adjustment amount, and a terminal device for adjusting the transmission dummy light, A wavelength block that transmits a control signal for adjusting the intensity of the dummy light by the dummy light adjustment amount, an analysis / control signal generator, and a dummy whose intensity is adjusted for each wavelength block according to the control signal A terminal device is provided, comprising: a dummy light generation / adjustment unit that generates light.

Furthermore, according to the present invention, an optical signal interruption is detected based on a signal interruption detector that detects an optical interruption signal in units of wavelength blocks and an optical signal interruption detected by a signal interruption detector included in each terminal device. A portion where the transmission dummy light according to the location is adjusted, a portion for obtaining a set of wavelength blocks and a dummy light adjustment amount, and a terminal device for adjusting the transmission dummy light, A dummy light whose intensity is adjusted for each wavelength block in accordance with the control signal sent from the information analysis / control signal generating apparatus that transmits a control signal for adjusting the intensity of the dummy light by the amount of dummy light adjustment. There is provided a terminal device including a dummy light generation / adjustment unit for generation.

Further, according to the present invention, based on the optical signal interruption in units of wavelength blocks detected by the signal interruption detection unit included in each terminal device, the location where the optical signal interruption occurred and the transmission according to the location A portion for obtaining a set of a terminal station and a wavelength block to adjust dummy light and a dummy light adjustment amount, and a terminal light device for adjusting the transmission dummy light to the dummy station by the dummy light adjustment amount by the wavelength block. There is provided an information analysis / control signal generation apparatus characterized by comprising a part for transmitting a control signal for adjusting the intensity.

According to the present invention, when a cable disconnection failure occurs, it is possible to prevent the channel power from increasing, and thus it is possible to prevent the transmission characteristics from deteriorating due to the nonlinear effect of the transmission path.

It is a conceptual diagram which shows the example of an optical submarine cable system. It is a conceptual diagram of the optical submarine cable system which has the structure for demonstrating this invention. FIG. 3 is a block diagram illustrating a configuration of an optical Add / Drop circuit illustrated in FIG. 2. It is a block diagram which shows the structure of the terminal station apparatus shown in FIG. FIG. 3 is a conceptual diagram showing how dummy light intensity is adjusted when a cable break occurs between an OADM-BU and a branch-side terminal device in the optical submarine cable system shown in FIG. 2. FIG. 3 is a diagram illustrating a part of a table used by an information analysis / control signal generation unit illustrated in FIG. 2. It is a figure which shows the remaining part of the table which the information analysis and control signal generation part shown in FIG. 2 uses.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

In a submarine cable system that employs an optical add / drop device, (1) a dummy light for main signal relief at the time of cable disconnection failure is placed in the signal band, and (2) when the cable disconnection failure occurs, By adjusting the output, the transmission characteristic deterioration of the main signal is suppressed.

The optical submarine cable system shown in FIG. 1 includes

terminal stations

101, 102, 103, and 111 installed at a landing station, a transmission path 108 laid on the seabed,

optical repeaters

113, 115, 117, 107, 119, BU (Branching Unit) 104 and 105 are included. In addition, landing stations (A and B stations) 101 and 102 that directly transmit and receive optical signals without branching are trunk stations, and landing stations (C and D stations) 103 and 111 that transmit and receive signals to be branched. Called a branch station.

There are two types of BU: one that branches in fiber units and one that inserts and branches in wavelength units. The latter is called OADM-BU. Since OADM-BU is generally known and can insert and branch only the desired wavelength, it is sufficient to install the minimum necessary terminal equipment at the landing station, which is expected to provide cost advantages. The

FIG. 2 shows an optical submarine cable system according to an embodiment of the present invention. The optical submarine cable system according to the present embodiment includes a terminal device 101 installed in one trunk station (A station), a terminal device 102 installed in the other trunk station (B station), and a branch station (C station). Terrestrial terminal station device 103 installed in the network, OADM-BU 104 for adding / dropping wavelength-multiplexed optical signals in units of wavelength bands, transmission path 108 for transmitting optical signals, and optical signal loss in the transmission path 108 are compensated It includes a communication path 109 used to connect the

optical repeaters

105, 106, and 107 and the

land terminal devices

101, 102, and 103 and exchange information with each other.

The OADM-BU 104 includes optical Add / Drop circuits 104-1 and 104-3 that branch signals from the trunk side and multiplex signals from the branch side.

Each of the optical Add / Drop circuits 104-1 and 104-3 includes a wavelength blocker 104-1-1 and a light combining unit 104-1-3, as shown in FIG. The wavelength blocker 104-1-1 is generally a band rejection filter. However, in the example of FIG. 3, the wavelength blocker 104-1-1 is a high band filter that blocks an optical signal of a long wavelength block (long wave band). In the example of FIG. 3, the light combining unit 104-1-3 combines a short wavelength block (short wave band) optical signal and a long wavelength block optical signal.

The signal is transmitted from the trunk signal wavelength band (trunk signal block) 201 transmitted / received between the

terminal station apparatuses

101 and 102, from the terminal station apparatus 101 of the trunk station, branched by the OADM-BU 104, and then the end of the branch station. Drop signal wavelength band (Drop signal block) 202 received by station device 103, transmitted from branch station terminal device 103, multiplexed by OADM-BU 104, and received by trunk

station terminal devices

101 and 102 Add signal wavelength band (Add signal block) 203. Further, the dummy light 211 is generated by the

land terminal devices

101, 102, and 103, and is disposed within the band of each signal wavelength band (signal block). It is also possible to arrange a plurality of dummy lights. The effect of arranging a plurality of dummy lights is that the optical power borne by each dummy light wave can be reduced.

Each of the

optical repeaters

105, 106, and 107 includes APCs (Automatic Pump Power Controllers) 105-1 and 105-3, respectively, by keeping the pumping light output constant, regardless of the power of the input optical signal. An optical signal with a substantially constant power is output.

FIG. 4 shows a configuration example of the

terminal device

101, 102, 103. The terminal device generates dummy light and adjusts the output power of the dummy light generation / adjustment unit 101-7, and the optical signal disconnection (signal disconnection) from the submarine cable is also referred to as a wavelength block ("subband"). .) Analyzing signal interruption information from the signal interruption detection unit 101-13 detected in units and the signal interruption detection units 101-13 of the

terminal devices

101, 102, 103, and generating a signal for output control of dummy light Information analysis / control signal generation unit 101-5, optical transmission / reception device 101-1 for transmitting / receiving optical signals, optical signal from optical transmission / reception device 101-1 and dummy light from dummy light generation / adjustment unit 101-7 are combined. Wave (Wavelength Division Multiplexing), optical multiplexing unit 101-9 for sending to the submarine cable, demultiplexing the signal from the submarine cable (wavelength Division Demultiplexing), and optical transceiver 101- Including optical demultiplexing section 101-11 to be sent to.

The signal loss detection unit 101-13 has the function of an optical spectrum analyzer, and determines that a signal is lost when there is no signal in each signal wavelength band.

The dummy light generation / adjustment unit 101-7, the optical multiplexing unit 101-9, the optical demultiplexing unit 101-11, and the signal break detection unit 101-13 are referred to as an optical multiplexing / demultiplexing device 101-3.

The signal analysis / control signal generation unit 101-5 may be provided in any one of the

terminal devices

101, 102, and 103, or may exist as a single device. 4 shows that the control signal 117 is sent to the same terminal device as the terminal device including the signal analysis / control signal generator 101-5. However, the present invention is not limited to this, and is sent to any one of the

terminal devices

101, 102, and 103. That is, the signal analysis / control signal generation unit 101-5 collects signal disconnection information from the signal disconnection detection units 101-13 of all managed terminal devices, analyzes them, and adjusts the intensity of the dummy light. As a result of this analysis, the set of terminal devices and wavelength blocks that need to be adjusted and the amount of adjustment are obtained, and the dummy light generation / adjustment of the terminal device that needs to adjust the intensity of the dummy light accordingly Information on the wavelength block and the adjustment amount is transmitted to the unit 101-7. A specific example will be described later.

Conventionally, dummy light was sometimes used, but this was used only to compensate for the shortage of optical signals when the number of operating optical transceivers 101-1 was small.

In the example shown in FIG. 5, the power of the signal wavelength band that is not input to the OADM-BU 104 due to cable disconnection is given to the dummy light, so that the main signal is output from the OADM-BU 104 and amplified by the

optical repeaters

105 and 106 at the subsequent stage. It is possible to keep the channel power constant. The dummy light adjusted at this time is dummy light in the wavelength block of the main signal. It is not the station on the side where the cable break has occurred but the dummy light arranged in the signal transmitted from the other station.

Dummy light adjustment is performed by the optical

transmission terminal devices

101 and 102 installed at the landing station.

Hereinafter, a specific procedure will be described below by taking the branch side cable disconnection failure as shown in FIG. 5 as an example.
1) The

terminal devices

101 and 102 indicate that the

terminal device

101 and 102 are not receiving a signal (Add signal) from the terminal device 103 that should be normally received. It is detected by the signal loss detection unit 101-13.
2) In this example, the information analysis / control signal generator 101-5 of the terminal device 101 is used. In this case, the signal break detection unit 101-13 of the terminal station device 101 and the signal break detection unit 101-13 of the terminal station device 102 respectively receive the signal break information 115 and the information analysis / control signal generation unit of the terminal device 101 101-5.
3) The information analysis / control signal generation unit 101-5 of the terminal device 101 analyzes the signal disconnection information, specifies the cable disconnection failure section, and sends the necessary control signal 117 to the dummy light generation / adjustment unit of the terminal device 101. 101-7 and the dummy light generation / adjustment unit 101-7 of the terminal device 102.
4) The dummy light generation / adjustment unit 101-7 of the terminal device 101 and the dummy light generation / adjustment unit 101-7 of the terminal device 102 that have received the command change the power of the dummy light.

If the power of the dummy light is not adjusted, the total power after multiplexing in the OADM-BU 104 is reduced by the lost signal wavelength band because one wavelength block is lost. However, the reduced power can be compensated by adjusting the power of the dummy light. Therefore, it is possible to prevent each optical signal from being excessively amplified by the APC of the

repeaters

105 and 106, thereby preventing deterioration of transmission characteristics due to the nonlinear effect of the transmission path.

When a plurality of dummy lights are arranged in the same wavelength block, the necessary power may be equally distributed. For example, when the number of signal wavelengths lost due to cable disconnection is large and the power to be complemented is large, the load of dummy light per wave can be reduced by providing a plurality of dummy lights.

Considering the branch-side cable disconnection failure as shown in FIG. 5, the ratio of the power of the dummy light arranged in the trunk signal and the trunk signal band to the power of the dummy light arranged in the Add / Drop signal and the Add / Drop signal band. Is n: m. Then, the total power P_t [mW] is obtained after the dummy light arranged in the trunk signal and the trunk signal band and the dummy light arranged in the Add / Drop signal and the Add / Drop signal band are combined.

The absolute amount Δ of the power that is reduced by the disappearance of the signal from the branch side (the dummy light arranged in the Add signal and the Add signal standby) is a linear scale.
Δ = (P_t * m) / (m + n) [mW]
It becomes.
When the output power per dummy light before adjustment is P_d [mW], the number of dummy lights to be controlled is d, and the power of all the dummy lights to be controlled is adjusted equally, one dummy light after adjustment The ratio between the power per unit and the power per dummy light before adjustment is a linear scale.
(P_d + (Δ / d)) / P_d = 1 + (P_t * m) / (P_d * (m + n) * d)
It becomes.

In addition, at the time of the initial construction of the submarine cable system, adjustment is performed so that the strength of the Add signal transmitted from the terminal device 103 and the strength of the Drop signal transmitted from the

terminal devices

101 and 102 are equal.

If the ratio of trunk signal and Add / Drop signal is fixed, the location where cable breakage has occurred and the amount of dummy light adjustment can be uniquely determined. By providing the information analysis / control signal generation unit 101-5, the processing time spent for control can be shortened.

As the dummy light, CW (Continuous Wave) dummy light and ASE (Amplified Spontaneous Emission) dummy light can be considered.

It is possible to add new dummy light instead of adjusting the output of dummy light.

Further, in the example of FIG. 5, only the intensity of the dummy light in the trunk signal block is increased, but in this way, the intensity of the optical signal used in the output of the APC of the

optical repeaters

105 and 106 is increased. It may become weaker than the allowable range. In order to avoid this, the intensity of the dummy light in the drop signal block is reduced or the dummy light is eliminated.

Next, details of the operation of the information analysis / control signal generation unit 101-5 will be described.

The information analysis / control signal generation unit 101-5 has tables as shown in FIGS.

The table shown in FIG. 6 is a diagram showing a correspondence relationship between a failure section and a combination of signal interruption of each wavelength block (wavelength band) of each input of each terminal device (station). This combination is referred to as a failure pattern. FIG. 7 is a table showing each wavelength block (wavelength band) and adjustment amount of each output of the terminal device (station) that requires adjustment of the intensity of the dummy light for each failure pattern. In FIG. 7, all adjustment amounts are expressed as xxdB, but the actual adjustment amount is an adjustment amount calculated by a calculation method similar to the calculation method described above. This is calculated in advance and written in the table of FIG.

Therefore, if the information analysis / control signal generation unit 101-5 detects any of the failure patterns in FIG. 6, the dummy light generation / adjustment unit that needs to adjust the intensity of the dummy light according to the table in FIG. Information identifying the dummy light generation / adjustment unit 101-7 that needs to be adjusted and information indicating the adjustment amount are transmitted to the terminal device including 101-7.

5 shows the failure pattern No. This is the case when 1 occurs.

Although representative embodiments of the present invention have been described in detail, various changes, substitutions and alternatives may be made without departing from the spirit and scope of the invention as defined in the claims. It should be understood. Moreover, even if the claim is amended in the application procedure, the inventor intends that the equivalent scope of the claimed invention is maintained.

This application is based on Japanese Patent Application No. 2009-068004 (filed on Mar. 19, 2009), and claims the priority of the Paris Convention based on Japanese Patent Application No. 2009-068004. The disclosure of Japanese Patent Application No. 2009-068004 is incorporated herein by reference to Japanese Patent Application No. 2009-068004.

The present invention can be used for an optical submarine cable system, a land optical communication system, and the like.

101, 102, 103 Terminal equipment 101-1 Optical transceiver 101-3 Optical multiplexer / demultiplexer 101-5 Signal analysis / control signal generator 101-7 Dummy light generator / adjuster 101-9 Optical multiplexer 101-11 Optical Demultiplexer 101-13 Signal break detector 104 OADM-BU
105, 106, 107 Optical repeater 105-1, 105-3 APC
108 Transmission path 201 Trunk signal block 202 Drop signal block 203 Add signal block

Claims

Based on the optical signal interruption in units of wavelength blocks detected by the signal interruption detection unit included in the terminal equipment at each location, the location where the optical signal interruption occurred and the terminal to adjust the transmission dummy light corresponding to that location Obtaining a set of device and wavelength block and a dummy light adjustment amount;
Transmitting a control signal for adjusting the intensity of the dummy light by the amount of the dummy light adjustment in the wavelength block to the terminal device to adjust the transmission dummy light; and
An optical signal level adjustment method comprising:
The optical signal level adjusting method according to claim 1,
An optical signal level adjusting method, further comprising a step of detecting an optical signal interruption by a signal interruption detection unit included in each terminal device.
The optical signal level adjustment method according to claim 1 or 2,
An optical signal level adjusting method, further comprising: generating dummy light whose intensity is adjusted for each wavelength block in accordance with the control signal.
The optical signal level adjustment method according to claim 3,
An optical signal level adjusting method, wherein the number of dummy lights is adjusted instead of adjusting the intensity of the dummy lights.
A signal break detector for detecting a light break signal in units of wavelength blocks;
Based on the optical signal interruption detected by the signal interruption detector included in each terminal apparatus, the terminal apparatus and the wavelength block where the transmission dummy light should be adjusted in accordance with the location where the optical signal interruption occurred. A part for obtaining a set of and a dummy light adjustment amount,
A portion that transmits a control signal for adjusting the intensity of the dummy light by the amount of the dummy light adjustment in the wavelength block to the terminal device to adjust the transmission dummy light;
A dummy light generation / adjustment unit that generates dummy light whose intensity is adjusted for each wavelength block according to the control signal;
A terminal device comprising:
The terminal device according to claim 5,
The dummy light generating / adjusting unit adjusts the number of dummy lights instead of adjusting the intensity of the dummy lights.
A signal break detector for detecting a light break signal in units of wavelength blocks;
Based on the optical signal interruption detected by the signal interruption detector included in each terminal apparatus, the terminal apparatus and the wavelength block where the transmission dummy light should be adjusted in accordance with the location where the optical signal interruption occurred. A part for obtaining a set of and a dummy light adjustment amount,
According to the control signal sent from the information analysis / control signal generating device that sends a control signal for adjusting the intensity of the dummy light to the terminal device to adjust the transmission dummy light by the dummy light adjustment amount. A dummy light generating / adjusting unit for generating dummy light whose intensity is adjusted for each wavelength block;
A terminal device comprising:
The terminal device according to claim 7,
The dummy light generating / adjusting unit adjusts the number of dummy lights instead of adjusting the intensity of the dummy lights.
Based on the optical signal interruption in units of wavelength blocks detected by the signal interruption detection unit included in the terminal equipment at each location, the location where the optical signal interruption occurred and the terminal to adjust the transmission dummy light corresponding to that location A part for obtaining a set of a device and a wavelength block and a dummy light adjustment amount;
A portion that transmits a control signal for adjusting the intensity of the dummy light by the amount of the dummy light adjustment in the wavelength block to the terminal device to adjust the transmission dummy light;
An information analysis / control signal generation device comprising:
An information analysis / control signal generation device according to claim 9,
The terminal device;
An optical signal level adjustment system comprising:
The optical signal level adjustment system according to claim 10.
In addition to the signal break detection unit, the terminal device further includes a dummy light generation / adjustment unit that generates dummy light whose intensity is adjusted for each wavelength block in accordance with the control signal. Optical signal level adjustment system.
The optical signal level adjustment system according to claim 11,
An optical signal level adjustment system that adjusts the number of dummy lights instead of adjusting the intensity of the dummy lights.
The optical signal level adjustment system according to claim 11 or 12,
An optical signal level adjustment system comprising a branching device having an optical add / drop multiplexing function.